Apparatus for cementing tubing strings in well bores



p 1963 H. H. FISHER, JR., ETAL 3,102,595

APPARATUS FOR CEMENTING TUBING STRINGS IN WELL BORES Filed April 25, 1960 2 Sheets-Sheet 1 5 Men/w 1/. EQ-HEE, J29.

INVENTORS. i ,3

44 m WWW 14 5400 WHNaLEgJQ."

p 3, 1953 H. H. FISHER, JR., ETAL 3,102,595

APPARATUS FOR CEMENTING TUBING STRINGS IN WELL BORES Filed April 25, 1960 2 Sheets-Sheet 2 M400 W HEMSLEE, J2.

INVENTORS.

BY I

. ,4rraewEys- United States Patent 3,102,595 APPARATUS FQIR (YEMENTING TUBING STRINGS EN WELL EURES Hiram H. Fisher, in, and Waldo W. Henslee, In, Houston, Tex., assignors to Baker Oil Tools, inc, Los Angeles, Califi, a corporation of California Filed Apr. 25, 196i), Ser. No. 24,311 17 Claims. (Cl. 166-156) The present invention relates to subsurface Well bore apparatus, and more particularly to apparatus useful in conducting cementing operations, and the like, in well bores.

In cementing a tubing string in a well bore, it is desirable to have a relatively unobstructed passage in the tubing string throughout its length to permit rapid pumping of the cement slurry down and around the tubing string, thereby securing laminar or turbulent flow of the cement slurry as it moves upwardly around the tubing string, and minimizing the possibility of channeling of the cement slurry during such upward movement. It is also desirable to have a device in the tubing string that will prevent back or return flow of cement slurry thereinto. Heretofore, a back pressure valve has been incorporated in the tubing string to prevent back flow of the slurry into the latter, but such valve places restrictions in the tubing that reduce the rate at which the cement slurry and other fluid or fluent substances can be pumped through and out of the tubing string.

An object of the present invention is to provide an apparatus adapted to form part of a tubing string, the apparatus including a tubular device having a relatively unrestricted passage and a plug device adapted to latch into the tubular device and function to prevent back flow of cement slurry, and the like, into the tubing string.

Another object of the invention is to provide an apparatus adapted to form part of a tubing string, and including a tubular device having a relatively unobstructed passage and a top cement plug adapted to seal against the wall of the tubing string during downward pumping of the cement slurry therethrough, the plug latching into the tubular device to prevent back flow of cement slurry, and the like, into the tubing string.

A further object of the invention is to provide an apparatus of the character above-indicated, in which the tubular device acts as a positive stop to limit the extent of downward movement of the plug device in the tubing string.

An additional object of the improved top cementing plug adapted to latch into a tubing string, to be prevented from then moving longitudinally in the tubing string in both directions.

This invention possesses many other advantages, and

invention is to provide an has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the inventon is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a longitudinal section through an apparatus embodying the invention, disclosing the plug device prior to latching into the tubular device;

FIG. 2 is a fragmentary section similar to FIG. 1, disclosing the latch portion of the plug device below the companion stop member of the tubular device;

FIG. 3 is a view similar to FIG. 2 of the plug device latched to the tubular device against upward movement with respect thereto;

FIG. 4 is a view similar to FIG. 1 of another embodiment of the invention; a

'FIG. 5 is a fragmentary or quarter longitudinal section of the plug device shown in FIG. 4 after the latch member of the plug device is moved below the companion stop of the tubular device;

FIG. 6 is a view similar to FIG. 5, showing the plug device latched against upward movement in the tubular device.

The forms of invention disclosed in the drawings will be described in connection with the cementing of a tubing string in a well bore. Such tubing strings are of substantially lesser diameter than casing or liner strings, and have correspondingly lesser cross sectional passage areas therethrough. As an example, a tubing string may have an outside diameter of 2 /8 inches and a substantially lesser internal diameter, whereas a typical casing string may have an outside diameter of 7 inches or 5 /2 inches. The incorporation of back pressure valve devices in casing or liner strings still allows sufiicient passage area through the valve device for the rapid pumping of cement slurry downwardly through the casing or liner string. However, incorporation of corresponding valve devices in a tubing string would inordinately restrict the effective passage area through the tubing string, and preclude rapid pumping of cement slurry therethrou gh.

Although the invention will be described with respect to a tubing string, it is to be understood that it is also applicable to casing strings, liner strings, and similar conduit strings disposed in a well bore.

in the form of invention shown in FIGS. 1, 2 and 3, a tubing string A is made up of a plurality of sections extending to the top of the hole and adapted to reach into the well bore to the desired depth. As shown, the tubing string includes an upper tubing section 10 and a lower tubing section 11 secured together by a suitable coupling device 12, 13. Specifically, a coupling collar 13 may be threadedly attached to the upper pin end 14 of the lower tubing section 11 and to the lower pin end 15 of another coupling or collar 12 having an upper threaded box 16 threadedly attached to the lower threaded pin 17 of an upper tubing section 16. The threaded box 16 terminates in a lower shoulder 13 which is longitudinally spaced from the lower end 19 of the upper tubing section it providing a circumferential continuous space or recess 20 adapted to receive a stop and latch ring 21that has an internal diameter slightly less than the internal diameter through the tubing section 10, so as to form an upwardly facing stop shoulder 22, that is preferably tapered in a downward and inward direction. As specifically shown, the stop and latch ring 21 is externally threaded to be threaded within the box 16 and engages the shoulder 18 at the lower end of the latter. To facilitate threading of the ring 21 in the box 16 to its position against the shoulder 18, circumferentially spaced radial slots 23 can be provided across the upperend of the ring for reception of a suitable tool (not shown) to be used in rotating the ring 21.

The tubing string A is lowered in the wall bore. The only restriction therein will be provided by the slight inward projection of the stop and latch ring 21 beyond the inside diameter of the tubing sections Iii, 11 themselves, as well as the coupling or collars :12, 13 forming part of the tubing string. Circulating fluid can be pumped down through the tubing string A, its flow therethrou gh being relatively unimpeded. After the tubing string Alias been lowered to the required depth in the well bore, the required quantity of cement slurry is pumped down the tubing string, and such cement slurry 'will pass in a comparatively unimpeded manner downwardly therethrough. It can be 3 pumped rapidly out of the tubing string to how upwardly through the space in the well bore around the tubing string and cement the latter in place.

A top cement plug 25 is placed at the upper end of the charge of cement slurry and displacement fluid is pumped down the tubing A on top of this cementing plug to prevent comingling between the displacement fluid and the cement slurry. As shown, the top cementing plug 25 includes a pliant, elastic member 26 having longitudinally spaced lip or wiper portions 27 adapted to slidably seal against the wall of the tubing string A. The lower portion 28 of this pliant, elastic member is molded Within a metallic sleeve 2%, this sleeve having a lowerflange 39 on which a pliant, elastic latch ring 31 is supported, this latch ring being molded on the periphery of the sleeve. The lower flange 3% has a diameter slightly less than the inside diameter of the stop and latch ring 21 secured in the coupling space 2.0 between the'shoulder l8 and the lower end '19 of the upper tubing section whereas the pliant, elastic latch ring 31, which is made of rubber or rubber-like material, has a diameter substantially equalling the ID. of the tubing string A so as to slidably seal along the wall of the tubing string as the cementing plug is pumped downwardly therethrough. Thee lower portion 32 of the rubber or rubber-like latch ring 31 is tapered in a downward and inward direction, being en-gageable with the upper tapered guide 22 of the stop 21 and effecting an upward stretching of the rubber latch ring 31 through the stop ring 21 until the ring 31 is positioned below the stop ring.

It is to be noted that the rubber latch ring 31 only extends upwardly from the lower flange 39 along the sleeve 29 to a relatively short extent, its upper end 33 terminating a substantial distance below an upper flange or stop shoulder 34 on the sleeve. This upper stop flange 34 has a diameter substantially less than the inside diameter of the tubing sections 10, 11, but greater than the inside diameter of the stop ring 21. The lower end 35 of the flange 34 is tapered to conform to the upper tapered surface 22 of the stop and latch ring 21.

The cement plug 25 moves down through the tubing string A to force cement slurry ahead of it. When the rubber latch ring 31 engages the tapered guide 22, the rubber is elongated and stretched upwardly along the sleeve 29 to decrease its outside diameter and enable it to squeeze completely through the latch ring 21 and then re-expand outwardly against the wall of the tubing string portion below the stop ring, such as the inner wall 36 of the coupling or collar 12. The rubber ring 31 can occupy a downward position below the stop ring Zll as determined by engagement of the stop shoulder 35 with the upper end 22 of the tapered guide, such as shown in FIG. 2, which will preclude further downward movement of the cementing plug 25 in the tubing string A and insure that there is some cement slurry in the tubing string below the location of the. stop ring 21.

' The building up of pressure at the top of the well bore will advise the operator that the cementing plug 25 has been arrested by the stop and latch ring 21. Downward pumping of fluid can then be discontinued and the pressure relieved. The cement slurry may tend to flow back into the tubing string A, shifting the cementing plug 25 upwardly in the tubing string. However, the extent of upward shifting is small, being limited by engagement of the upper end 33 of the pliant, elastic latch ring 31 with the lower end 37 of the stop ring 21. Since such lower end 37 is substantially normal to the axis of the apparatus, the rubber stop ring 31 will merely be deformed or compressed against the stop ring 21, precluding further upward movement of the plug 25 in the tubing string. Accordingly, the, plug 25 has been latched in the tubing string A against upward movement, preventing back or return flow of fluid into the tubing string. it is also prevented from moving downwardly in the tubing string by r iengagement of the stop shoulder 35 with the upper end or stop surface 22 of the metallic latch ring Zll.

The plug 25 may remain in the tubing string A in the event it is unnecessary to have a clear passage therethrough from the region of the plug downwardly to an opening or the lower shoe (not shown) of the tubing string, as for example, when the tubing string A is perforated at some point above the latching position of the plug, and is to be produced through such upper perforations. In the event, however, that the bore through the tubing string A is unobstructed, then it is preferred to have thee sleeve 29 and the stop and latch ring 21 made of readily drillable material, such as cast iron or aluminum,

so that a drill bit (not shown) can be lowered through the tubing string A and suitably manipulated to disintegrate the plug 25 and the stop and latch ring 211, the drilled pieces or particles being circulated, in a known manner, from the tubing string. The bore through the tubing string A will then be unobstructed.

In the form of invention shown in FIGS. 4, 5 and 6, a stop and latch ringlla is mounted in the coupling space 2811 between adjacent tubing sections lit, 11. Thus, the upper tubing section it has a threaded pin 17 threadedly secured to a coupling collar 13, which is, in turn, threadedly secured to the threaded pin 14 at the upper end of the lower tubing section 11. in the coupling space 20a includes a depending skirt 4% that extends downwardly along the inner wall 41 of the lower tubingsection ill. The upper end 2211 of the stop ring 21a is tapered in a downward and inward direction and the inside diameter through the stop ring 21a and its skirt 44) is less than the inside diameter through the tubing string A, there being a counterbore 42 at the upper portion of the'stop ring 21a, the base 22b of which is tapered in a downward and inward direction to provide a stop shoulder against which the stop shoulder 35 or flange 3d of the sleeve portion 29 of the cementing plug 25 will seat. As in the other form of the invention, the lower flange 30 on the sleeve has an external diameter slightly less than the internal diameter through the stop ring 21a, so as to pass completely therethrough.

In all material respects, the cementing plug 25 is substantially the same as the cementing plug disclosed in H68. 1, 2 and 3, being molded to the metallic sleeve 29, which can be made of aluminum or cast iron, and having the pliant, elastic latch ring 31 molded thereto and resting on the bottom flange 30. This ring 31 can slidably seal against the wall of the tubing string A. When the top cementing plug 25 reaches the stop ring Zia, the tapered guide surfaces 22a, 22b will elongate the latch ring 31 and stretch it upwardly, whereby it will squeeze completely through the stop ring and then re-expand against the wall 41 of the lower tubing section 11 below the stop ring 21a. The upper flange 3 will come to rest within the counterbore 42 and against the tapered stop shoulder 22b forming the base of the counterbore, further downward movement of the cementing plug being prevented (FIG. 5). Upward movement of the cementing plug 25 will be limited by engagement of the rubber or rubber-like latch ring 31 itself against the lower end 43 of the stop ring 21a, as shown in FIG. 6.

The stop ring 21a and sleeve 29' are preferably made i of readily drillable material, as in the other form of invention, so. that if a clear passage through the tubing string'A is desired, the cementing plug and latch ring can be disintegrated, as by use of a suitable drill bit.

We claim:

1. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and havingan inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of The stop ring 21a disposed the -tubing string for sealing with the tubing string and the tubular means, said plug including a second member below said seal means and having an outside diameter greater than the inside diameter of said first member; one of said members being of a pliant, elastic material to allow said second member to move down through said first member to a position therebelow, said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

2. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a second member below said seal means and having an outside diameter greater than the inside diameter of said first member; one of said members being of a pliant, elastic material to allow said second member to move down through said first member to a position therebelow; stop means above said second member for limiting downward movement of said plug in said tubular means after said second member has moved below said first member; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

3. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means comfor-ming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant, elastic second member below said seal means and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said second member being engageable with said first member, after said second member is moved below said first member, to prevent upward movement of said plug in said tubular means.

4. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string :and having seal means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant,

' elastic second member below said seal means and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; stop means above said second memher for limiting downward movement of said plug in said tubular means after said second member is moved below said first member; said second member being engageable with said first member, after said second member is moved below said first member, to prevent upward movement of said plug in said tubular means.

5. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a second member having an outside diameter greater than the inside diameter of said first member; one of said members being of a pliant, elastic material to allow said second member to move down through said first member to a position therebelow; stop means on said plug engageable with the inwardly projecting portion of said first member for limiting downward movement of said plug in said tubular means after said second member is moved below said first member; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

6. In apparatus for the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant, elastic second member having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; stop means on said plug engageable with the inwardly projecting portion of said first member for limiting downward movement of said plug in said tubular means after said second member is moved below said first member; said second member being engageable with said first member, after said second member is movedbelow said first member, to prevent upward movement of said plug in said tubular means.

7. In apparatus of the character described: tubular means adapted to form part of a tubing string to be dis posed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having a pliant, elastic portion conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a sleeve secured to said pliant, elastic portion and a pliant, elastic second member secured to said sleeve and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said sleeve having a flange engageable with said first member after said second member has moved below said first member for limiting downward movement of said plug in said tubular means; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

8. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having a pliant, elastic portion conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a sleeve secured to said pliant, elastic portion and a pliant, elastic second member secured to said sleeve and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said sleeve having a flange, engageable with said first member after said second member has moved below said first member for limiting downward movement of said plug in said tubular means; said second member being engageable with said first member, after said secnd member has moved below said first member, to prevent upward movement of said plug in said tubular means; the lower end of said first member and the upper end of said second member engageable therewith being substantially normal to the axis of said tubular means.

9. A cementing plug adapted to be pumped down a tubular string disposed in a well bore, including a pliant, elastic portion adapted to slidably seal with the wall of the tubular string, a sleeve surrounding and secured to said pliant, elastic portion below its region that seals with the tubular string, and a pliant, elastic annular member secured to the exterior of said sleeve and having an external diameter at its region surrounding said sleeve substantially the same as the external diameter of said pliant, elastic portion.

7 10. A cementing plug adapted to be pumped down a I tubular string disposed in a Well bore, including a pliant,

elastic portion adapted to slidably seal with the wall of the tubular string, a sleeve secured to said pliant, elastic portion and having a stop fiange of an external diameter substantially less than the external diameter of said pliant, elastic portion, and a pliant, elastic annular member'secured to the exterior of said sleeve substantiallybelow said stop flange and having an external diameter substantially greater than the external diameter of said flange.

11. In apparatus of the character described: tubular means adapted to form part of a tubular string to be disposed in a well bore and comprising a pair of tubular parts connected to one another to provide an internal annular recess therebetween; a first annular member disposed in said recess and having an internal diameter less than the internal diameter of said tubular parts to project laterally inwardly of the adjacent walls of said tubular parts; a plug adapted to be pumped down the tubing string and into said tubular parts and having sealing means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a second member having an 'outside diameter greater than the inside diameter of said first annular member; one of said members being of a pliant, elastic material to allow said second member to move down through said first member to a position therebelow, said second member being engageable with said first annular member, after said second member has moved below said first annular member, to prevent upward movement of said plug in said tubular means.

12. In apparatus of the character described: tubular means adapted to form pant of a tubular string to be disposed in a well bore and comprising a pair of tubular parts connected to one another to provide an internal annular recess therebetween; a first annular member disposed in said recess and having an internal diameter less than the internal diameter of said tubular parts to project laterally inwardly of the adjacent walls of said tubular parts; a plug adapted to be pumped down the tubing string and into said tubular parts and having sealing means conforming to-ithe inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant, elastic second member having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

13. In apparatus of the character described: tubular means adapted to form part of a tubular string to be d disposed in a well bore and comprising a'pair of tubular parts connected to one another to provide an internal annular recess therebetween; a first annular member disposed in said recess and having an internal diameter less than the internal diameter of said tubular parts to project laterally inwardly of the adjacent walls of said tubular parts; a plug adapted to be pumped down the tubing string and into said tubular parts and having sealing means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant, elastic second member having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; stop means on said plug engageable with said first member for limiting downward movement of said plug in said tubular means after said I second member has moved below said first member, said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means. 7

14. In apparatus of the character described: tubular means adapted to form pant of a tubing string to be disposed'in a bore hole, a first member secured within said tubular means and having an inside diameter less than the, inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a' plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a second member below said seal means and having an outside diameter greater than the inside diameter of said first member; one of said members being of a pliant, elastic material to allow said second member to move down through said first member to a positiontherebelow; stop means on said plug above said second member engageable with the inwardly projecting portion of said first member for limiting downward movement of said plug in said tubular means after said second member is moved below said first member; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

15. In apparatus of the character described: tubular means adapted to form part of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having seal means conforming to the inside diameter of'the tubing string for sealing with the tubing string and the tubular means, said plug including a pliant, elastic second member'below said seal means having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; stop means on said plug above said second member engageable with the inwardly projecting portion of said first member for limiting downward movement of said plug in said tubular means after said second member is moved below said first member; said second member being engageable with said first mem-.

her, after said second member is moved below said first member, to prevent upward movement of said plug in a plug adapted to be pumped down the tubing string and having a pliant, elastic portion conforming to the inside diameter of the tubing string for sealing With the tubing string and the tubular means, said plug including a sleeve secured to said pliant, elastic portion and a pliant, elastic second member below said pliant, elastic portion and secured to said sleeve and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said sleeve having a flange above said second member engageable with said first member after said second member has moved below said first member for limiting downward movement of said plug in said tubular means; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means.

17. In apparatus of the character described: tubular means adapted to form par-t of a tubing string to be disposed in a bore hole, a first member secured within said tubular means and having an inside diameter less than the inside diameter of the tubular means to project laterally inwardly of the adjacent wall of the tubular means; a plug adapted to be pumped down the tubing string and having a pliant, elastic portion conforming to the inside diameter of the tubing string for sealing with the tubing string and the tubular means, said plug including a sleeve secured to said pliant, elastic portion and having a lower flange movable through said first member, said plug fur- 10 ther including a pliant, elastic second member secured to said sleeve above and resting on said lower flange and having an outside diameter greater than the inside diameter of said first member, whereby said second member can squeeze downwardly through said first member to a position therebelow; said sleeve having an upper flange above said second member engageable with said first mem ber after said second member has moved below said first member for limiting downward movement of said plug in said tubular means; said second member being engageable with said first member, after said second member has moved below said first member, to prevent upward movement of said plug in said tubular means; the lower end of said first member and the upper end of said second member engageable therewith being substantially normal to the axis of said tubular means.

References Cited in the file of this patent UNITED STATES PATENTS 2,148,401 Ellis Feb. 21, 1939 2,275,655 Robbins Mar. 10, 1942 2,559,536 Haynes et a1 July 3, 1951 2,621,742 Brown Dec. 16, 1952 2,662,602 Schnitter Dec. 15, 1953 2,717,645 Schnitter Sept. 13, 1955 2,921,631 Gage Jan. 19, 1960 3,006,415 Burns et a1 Oct. 31, 1961 

9. A CEMENTING PLUG ADAPTED TO BE PUMPED DOWN A TUBULAR STRING DISPOSED IN A WELL BORE, INCLUDING A PLIANT ELASTIC PORTION ADAPTED TO SLIDABLY SEAL WITH THE WALL OF THE TUBULAR STRING, A SLEEVE SURROUNDING AND SECURED TO SAID PLIANT, ELASTIC PORTION BELOW ITS REGION THAT SEALS WITH THE TUBULAR STRING, AND A PLIANT, ELASTIC ANNULAR MEMBER SECURED TO THE EXTERIOR OF SAID SLEEVE AND HAVING AN EXTERNAL DIAMETER AT ITS REGION SURROUNDING SAID SLEEVE SUBSTANTIALLY THE SAME AS THE EXTERNAL DIAMETER OF SAID PLIANT, ELASTIC PORTION. 